1. Field of the Invention
This invention is directed to a system and to a method. More specifically, this invention relates to an improved system for use in conjunction with endoscopic instrumentation in laparoscopic surgery. This unique system incorporates a pressurizable reservoir containing the irrigation fluid, an elongated conduit, connected at the proximal end to an instrument and at its distal end to a float valve of unique design and construction wherein a sensing means in such valve can detect the level of pressurized fluid remaining in the reservoir and close the valve in response to depressed fluid level. The automatic activation of this valve in response to depression of the fluid level within the reservoir, prevents the pressurizing gas from inadvertent introduction into the operative field.
2. Description of the Prior Art
The art of endoscopy and laparoscopic surgery (and the drawbacks associated therewith) are wellknown to those skilled in the art and need not be repeated herein. Whether the endoscope is rigid or flexible, equipped with a telescope and light source or fluoroscopic means required for guidance and manipulation thereof within the operative field, one problem is generally common to both types of systems; that is, the difficulties encountered in respect to the infusion and suction of fluid into the operative field to allow for clearance, identification and targeting of the appropriate target tissue within the operative field.
The applicant has filed for patent protection on a unique "trumpet valve" for use in endoscopic surgery, application Ser. No. 07/470,771 (filed Jan. 21, 1990), now U.S. Pat. No. 5,188,591. Applicant herein incorporates by reference the discussion of the relevant art endoscopic instruments contained in such application, including the discussion of U.S. Pat. Nos. 4,191,191; 3,967,625; 4,824,434; 4,735,194; 4,795,424; 4,504,493; 4,493,320; 4,423,727; 4,217,819; and 4,795,424. The foregoing patents generally describe different endoscopic instruments and systems, and are useful as background, in appreciation of the historical development of the art endoscopy, and some of the problems associated with the art. To the extent they are relevant, reference thereto is made and is helpful as providing general background information and an aid of understanding of the instant invention.
In the operation of endoscopic instrumentation, more specifically, hydrodissection apparatus, a fluid reservoir (which reservoir is maintained under pressure) is connected through appropriate fluid channeling means to a probe tip. Typically the fluid level in the pressurized reservoir was monitored visually or was allowed to run out, such prior art systems being unreliable and often dangerous by exposure of the patient to inadvertent injection with a gas (CO.sub.2).
The use of float valves in a non-pressurized and pressurized environment to control the flow of fluid from a reservoir and seal off the channel from the reservoir when the fluid drops, is well known in the prior art. The following patents are representative of different flow valve designs, and the respective operation both in ambience pressures and in a pressurized environment.
U.S. Pat. No. 3,490,482; (to Sachs, et al) describes a liquid transfer system for circulation of photographic developer, and related chemicals, within a closed loop to effect multiple batch processing of photographic film and papers.
In the context of the Sachs invention, film developer chemicals, in liquid form, are forced under pressure from a reservoir (#14) in the film developer processing loop to a developer tank (#12). Upon completion of a development process, these same fluids are recycled back to the reservoir (#14) from the developer tank (#12). This process is repeated with fixer (hypo) from reservoir (#16). In operation of the fluid transfer from the respective reservoirs, a "ball valve" (#62) partially closes the orifice leading from these respective reservoirs, allowing for compressed air to also flow from the reservoir (#16) to the developer tank (#12). The reasons for such air flow is apparently to provide a degree of agitation to the developer chemicals.
U.S. Pat. No. 2,972,412 (to Lundeen) describes a float value assembly adapted for use in a water softener system; specifically in the fluid communication of brine, from the brine storage tank, to the water softener tank. The float valve is connected to the end of a section of tubing which is positioned within the brine tank and thereby allows for the program withdrawl of brine therefrom upon cycling of the water softener tank. Fluid transfer from one tank to the other can be effected by a simple pump located in the softener tank, or by passive siphon action. When the level of brine in the brine tank drops to an unacceptable level, the float valve responds by sealing the orifice in the base of the valve, thereby preventing air from being drawn from the brine tank into the softener tank. Where the fluids transfer from one tank to the other is based upon a passive siphon system, the sealing of a valve maintains the fluid within the conduit connecting one tank to the other, thus, preserving the siphon upon the restoration of the proper fluid level in the brine tank.
U.S. Pat. No. 4,132,238 (to Clark) describes a separator valve for use in waste stream discharge systems. The valve includes a cage and a float. The materials from which the float is constructed allow for movement thereof within the cage in response to changes in the specific gravity of the waste water discharge. Where the discharge is essentially oil free, that is, has a specific gravity approximating the specific gravity of the water, the float will remain buoyant. Where the specific gravity of the discharge drops below the specific gravity of the water, the float will respond by losing its buoyancy and moving to the floor of the cage, thereby sealing a orifice in the base of the cage, and preventing further discharge of the waste stream through the valve.
U.S. Pat. No. 3,227,173 (to Bernstein) describes a series of flotation type valves adapted for use in the clinical environment. All of the embodiments of the Bernstein concept involve the placement of a float within a container at least partially filled with a parenternal fluid. As parenternal fluid is passively (IV) or actively (syringe) withdrawn from the fluid container, these valves respond to the depressed fluid level within the container by sealing an orifice through which such fluid must pass.
U.S. Pat. No. 4,078,563 (to Tuseth) describes a disk valve for control of withdrawal of parenternal fluid from an inverted container. The valve is positioned within the neck of the container, and responds to withdrawal of fluid therefrom in much the same way as the more traditional design illustrated in the Bernstein patent discussed above.
As is evident from the foregoing, the use and adaptation of float valves to control, meter and arrest the flow of fluid from a container is common to a variety of environments and fluid containment vessels. The design of each float valve will of course vary with the specific vessel design, the fluid composition and the means used to effect transfer of fluid from its container through its valve to the discharge/withdrawal site.
As is further evident from the foregoing, valves are typically used in systems involving a passive transfer mechanism, that is fluid flow from the container through the float valve is generally accomplished by a combination gravity and siphon action. Where, however, fluid transfer is effected by means of an active transport mechanism, such as by pressurization of the fluid container, both the rate of fluid transfer and depression in the fluid level in the fluid reservoir will be greatly accelerated. In such an active fluid transport system, valve response must be more rapid and precise in order to avoid withdrawal of fluid below the level that is prescribed for such a system. This is particularly critical in dispensing of chemical fluids and in their use in endoscopic systems. Traditionally, the transfer of fluid in such active transport (endoscopic) systems has been monitored electronically. The valving in such system is typically effected through solenoid activation upon optical and/or electronic pressure sensing of fluid level. Notwithstanding the availability of such electronically activated systems, the float valve has been and remains the mechanism of choice. Unfortunately, such valves have typically lacked the response time and the precision necessary to effectively seal off fluid flow from a pressurized container and/or reservoir.